An automobile instrument panel has a structure in which a foamed polyurethane layer is disposed between a substrate and a surface skin formed from a vinyl chloride resin. Over time, the surface skin formed from the vinyl chloride resin discolors and experiences a reduction in heat aging resistance. One main cause of discoloration and so forth of the surface skin is a chemical reaction that occurs as a result of a tertiary amine used as a catalyst in formation of the foamed polyurethane layer migrating to the surface skin formed from the vinyl chloride resin. In order to prevent surface skin discoloring, a urethane integrated foamed molded product has been considered in which a granular catcher agent that captures volatile organic compounds produced in a foamed polyurethane layer and that is coated with an open cell foam sheet is provided near locations at which the edges of the foamed polyurethane layer are sealed by a surface skin and a substrate (for example, refer to PTL 1). However, there are sections where the surface skin and the foamed polyurethane layer are in contact in this urethane integrated foamed molded product and, as a result, surface skin discoloration due to the aforementioned chemical reaction cannot be prevented over a long period and heat aging resistance of the surface skin decreases.
On the other hand, a laminate has been considered in which a synthetic resin foamed layer is provided that joins a core material and a surface skin and in which the core material includes gas release holes for releasing gas produced in the foamed layer (for example, refer to PTL 2). However, the synthetic resin foamed layer and the surface skin are in contact in this laminate and, as a result, surface skin discoloration due to the aforementioned chemical reaction cannot be prevented over a long period and heat aging resistance of the surface skin decreases.
Furthermore, a molded product has been considered that includes a polyurethane molded product, a surface skin containing a vinyl chloride resin that covers at least one surface of the polyurethane molded product, and an amine catcher layer disposed between the polyurethane molded product and the surface skin (for example, refer to PTL 3). However, it is not possible to prevent migration of a tertiary amine to the surface skin formed from the vinyl chloride resin over a long period due to volatility of the amine catcher. Therefore, surface skin discoloration due to the aforementioned chemical reaction cannot be prevented over a long period and heat aging resistance of the surface skin decreases in this molded product.
On the other hand, a vinyl chloride resin composition for powder molding that includes a prescribed trimellitate plasticizer has been considered as a raw material for a surface skin of an automobile interior material (for example, refer to PTL 4). However, it is necessary to increase the blended amount of the plasticizer in order to improve heat aging resistance of a surface skin material that is obtained through powder molding of the vinyl chloride resin composition, which results in the surface skin material feeling sticky due to the plasticizer. A vinyl chloride resin composition for powder molding has also been considered that includes 100 parts by mass of vinyl chloride resin particles made from a vinyl chloride resin having an average degree of polymerization of at least 1,500 and 110 parts by mass to 150 parts by mass of a prescribed trimellitate plasticizer (for example, refer to PTL 5).